The disposal of hazardous waste is increasingly becoming a serious problem to industry as governmental regulations become tighter and tighter. Two leading technologies for disposing of hazardous wastes are landfills and combustion, or incineration. The terms "combustion" and "incineration" are used interchangeably herein. While the industry has historically preferred landfills over incineration, primarily because of cost, incineration is becoming more attractive. One reason tier this is because governmental regulations regarding landfills are becoming more restrictive. For example, in 1989 a new extended list of chemical streams which are banned from landfills went into effect. As industry turns toward incineration as the primary means of disposing of hazardous waste, they are also faced with tougher and tougher incineration restrictions. For example, the destruction and removal efficiency (DRE) ratings for incineration are presently set at 99.99% of most hazardous waste, and 99.9999% for polychlorinated biphenyls (PCBs).
This has created a substantial problem for industry. For example, in the petrochemical and oil producing states, the problem of cleaning-up contaminated sites and waste-oil pits is already of paramount importance, and is becoming even more acute. The quantity of waste oil contamination at oil field drilling sites has become a problem of great magnitude. The necessity of hauling the accumulated contaminated material from wide spread areas of contamination to a central decontamination site aggravates the problem considerably. Likewise, the problem of cleaning up abandoned petrochemical sites is even more severe.
The problem is particularly severe when hazardous waste is burned. This is because not only must the waste be disposed of before harm is done to the environment, but additionally, the destruction of any potentially toxic chemicals must be sufficiently complete so that the gases which evolve are non-hazardous. To completely decompose most of these chemicals, relatively highly efficient and high temperature combustion is needed to lower the cost of incineration, which is typically expensive.
The discharge stack emissions from an incineration means are typically of important concern for several reasons. For one reason, the public views stack emission plumes with suspicion and fears that the incinerator operator is discharging hazardous, or toxic gases into the atmosphere. Another reason is that the federal and state authorities have regulations governing stack emissions with regular monitoring, testing, and validation to insure that prescribed emission limits are not being exceeded.
U.S. Pat. No. 5,179,903 teaches a multistage closed loop incineration process for disposing of waste material wherein a portion of the resulting fuel gas stream is enriched with oxygen and recycled to the incineration means. The portion is scrubbed to remove acid gases and passed through a purification zone wherein any remaining contaminants are removed. This patent does not teach converting the waste to a fuel or gaseous product which can be either collected to produce chemicals or used to fuel a downstream combustion zone, such as a boiler, furnace, an internal combustion engine.
Therefore, there is a substantial need in the art for improved incineration processes which are able to meet the present destruction and removal efficiency requirements, as well as requirements in the foreseen future.